sight glass

[Julian]

Hi All,

I am just about to build several boilers and need sight glasses for the water level. Rather than the glass tube sort I am looking at the glass plate type. I plan to use my cnc mill to make the mountings for them to sandwich the glass on the boiler. My question is what glass can I use for this purpose? Will 6mm plate about 15mm by 50mm withstand the pressure? I plan to run at up to 75psi so the glass will need to obviously test to more than twice this. Some will be steel boilers and some will be copper.


Regards

Julian

 

[GWRdriver]

Jason,
I have a couple of comments, although I won't venture to answer your thickness x size question. The first comment is that I've seen quite a few "porthole" gauge glasses over the years and they all had two things in common - the boilers were run at less than 50psi, and they were all round. My other comment is that gauge glasses of any shape for steam service should be borsilicate glass (ie Pyrex or lab glass) with sealed edges. The sealing is done by reheating any cut or scored edge to a near molten state so as to seal potential sources of cracks.

 

[Jasonb]

You could make it with a standard tube and then fit a gauge glass protector over it which would make it look like the square type. No problems with sealing the edges and you know it will take the pressure.

http://www.heritagesteamsupplies.co...upplies/Water-Level-Gauges-&-Spares/p-297-197

J